Search

The prevalence of porcine reproductive and respiratory syndrome virus 1 (PRRSV1) isolates has continued to increase in Chinese swine herds in recent years. However, no effective control strategy is available for PRRSV1 infection in China. In this study, we generated the first infectious cDNA clone (rHLJB1) of a Chinese PRRSV1 isolate and subsequently used it as a backbone to construct an ORF2-6 chimeric virus (ORF2-6-CON). This virus contained a synthesized consensus sequence of the PRRSV1 ORF2-6 gene encoding all the envelope proteins. The ORF2-6 consensus sequence shared > 90% nucleotide similarity with four representative strains (Amervac, BJEU06-1, HKEU16 and NMEU09-1) of PRRSV1 in China. ORF2-6-CON had replication efficacy similar to that of the backbone rHLJB1 virus in primary alveolar macrophages (PAMs) and exhibited cell tropism in Marc-145 cells. Piglet inoculation and challenge studies indicated that ORF2-6-CON is not pathogenic to piglets and can induce enhanced cross-protection against a heterologous SD1291 isolate. Notably, ORF2-6-CON inoculation induced higher levels of heterologous neutralizing antibodies (nAbs) against SD1291 than rHLJB1 inoculation, which was concurrent with a higher percentage of T follicular helper (Tfh) cells in tracheobronchial lymph nodes (TBLNs), providing the first clue that porcine Tfh cells are correlated with heterologous PRRSV nAb responses. The number of SD1291-strain-specific IFNγ-secreting cells was similar in ORF2-6-CON-inoculated and rHLJB1-inoculated pigs. Overall, our findings support that the Marc-145-adapted ORF2-6-CON can trigger Tfh cell and heterologous nAb responses to confer improved cross-protection and may serve as a candidate strain for the development of a cross-protective PRRSV1 vaccine. [ABSTRACT FROM AUTHOR]

The Chinese fir Cunninghamia lanceolata (Lamb.) Hook. is an important timber conifer species in China. Much has been studied about Chinese fir, but the distribution of non-structural carbohydrates (NSCs) among different organs (needles, branch, stem, and roots) under drought stress remains poorly understood. In this study, we used one-year-old C. lanceolata plantlets to evaluate the effects of simulated drought under four water regimes, i.e., adequate water or control, light drought, moderate drought, and severe drought stress corresponding to 80%, 60%, 50%, and 40%, respectively of soil field maximum capacity on various NSCs in the needles, branch, stem and roots. The degree and duration of drought stress had significant effects on fructose, glucose, sucrose, soluble sugar, starch, and NSC content in various organs (p < 0.05). Fructose content increased in stem xylem, stem phloem, and leaves. Glucose and sucrose content declined in stem and branch xylem under light drought stress and moderate drought stress, and increased under severe drought stress conditions. Soluble sugars content declined, and starch content increased in leaf and branch phloem, but the latter could not compensate for soluble sugar consumption in the whole plant, and therefore, total NSCs decreased. Correlation analysis showed that a significant positive correlation existed in the soluble sugar content between leaves and roots, and between xylem and phloem in the stems and branches. Chinese fir appears to have different NSCs distribution strategies in response to drought stress, viz., allocating more soluble sugars to fine roots and increasing starch content in the needles, as well as ensuring osmosis to prevent xylem embolism. Our study may broaden the understanding of the various mechanisms that Chinese fir and other plants have to enhance their tolerance to drought stress. [ABSTRACT FROM AUTHOR]

Chinese fir (Cunninghamia lanceolata) is the most cultivated timber species in China, with a plantation area of 11 million ha. Due to its extensive geographical distribution, drought stress caused by the spatial and seasonal heterogeneity of precipitation has limited its survival and productivity. To facilitate the breeding of drought-tolerant clones and understand the inter-response mechanisms to drought stress, we screened two drought-tolerant (DT) clones and evaluated their differences in physiological and molecular response to drought. The results showed that the No. 228 clone (high-DT ability) had higher antioxidant enzyme abilities than the No. 026 clone (low-DT ability) under drought stress, e.g., peroxidase (POD), polyphenol oxidase (PPO), superoxide dismutase (SOD), and catalase (CAT). Transcriptome analyses revealed that 6637 genes and 1168 genes were up-regulated in No. 228 and No. 026 under drought stress, respectively, when compared to the control (CK). The genes may participate in response to drought-stimulated signal transduction, water/oxygen-containing compound synthesis, photosynthesis, and transmembrane transport functions. Particularly, under drought stress, 14,213 up-regulated and differentially expressed genes (DEGs) were observed in the No. 228 clone compared with the No. 026 clone, and 4274 up-regulated genes were differentially expressed (15-fold difference). These significant DEGs were involved in plant hormone signal transduction, flavonoid biosynthesis, peroxisomes, and other key pathways related to drought. Interestingly, under drought stress, two Chitinases (ClCHIs) and four POD genes (ClPERs) were induced to express in No. 228, which was consistent with the higher antioxidant enzyme activities in No. 228. A heat map of 49 DEGs revealed that dehydrin family genes, ion binding/transmembrane proteins, auxin receptor proteins, and ethylene-responsive transcription factors were significantly up-regulated under drought stress. The results can enhance our understanding of drought tolerance mechanisms and provide a guideline for screening DT genes and breeding drought-tolerant Chinese fir clones. [ABSTRACT FROM AUTHOR]

Since we first reported porcine reproductive and respiratory syndrome virus 1 (PRRSV1) wild type strains in mainland China in 2011, PRRSV1 infection has been detected in more than 20 provinces in China. During the routine investigation of PRRSV1 epidemiology in 2022, we isolated a novel PRRSV1 strain (SD1291) from an adult slaughter pig in Linyi, Shandong Province. The SD1291 could only be isolated with primary alveolar macrophages (PAMs), not with Marc-145 cells. In addition, the 2022 SD1291 isolate has higher in vitro replication efficacy than the 2014 PRRSV1 HLJB1 isolate in PAMs. Due to high genetic variation, the complete genome of SD1291 was determined by metagenomic sequencing, which showed that SD1291 shares the highest genome similarity (88.12%) with the PRRSV1 HeB47 isolate. Sequence alignment results identified a four-amino-acid deletion in nsp2 and a five-amino-acid deletion in the GP3 and GP4 overlap region of SD1291. A complete-genome-based phylogenetic tree showed that SD1291 is grouped with BJEU06-1-like PRRSV1 isolates. A piglets' challenge study showed that SD1291 can cause high fever (the highest is 41°C), reduced weight gain, mild lung consolidation, and interstitial pneumonia indicating that SD1291 is a pathogenic PRRSV1 isolate. Overall, this study first identified a novel pathogenic PRRSV1 isolate from an adult slaughter pig in China. Our findings also suggested that new PRRSV1 variants could escape the current PRRSV vaccination system and circulate in adult swine herds, which deserve more attention. [ABSTRACT FROM AUTHOR]

Due to the substantial genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV), commercial PRRS vaccines fail to provide sufficient cross protection. Previous studies have confirmed the existence of PRRSV broadly neutralizing antibodies (bnAbs). However, bnAbs are rarely induced by either natural infection or vaccination. In this study, we designed and synthesized a consensus sequence of PRRSV2 ORF2-6 genes (ORF2-6-CON) encoding all envelope proteins based on 30 representative Chinese PRRSV isolates. The ORF2-6-CON sequence shared > 90% nucleotide identities to all four lineages of PRRSV2 isolates in China. A chimeric virus (rJS-ORF2-6-CON) containing the ORF2-6-CON was generated using the avirulent HP-PRRSV2 JSTZ1712-12 infectious clone as a backbone. The rJS-ORF2-6-CON has similar replication efficiency as the backbone virus in vitro. Furthermore, pig inoculation and challenge studies showed that rJS-ORF2-6-CON is not pathogenic to piglets and confers better cross protection against the virulent NADC30-like isolate than a commercial HP-PRRS modified live virus (MLV) vaccine. Noticeably, the rJS-ORF2-6-CON strain could induce bnAbs while the MLV strain only induced homologous nAbs. In addition, the lineages of VDJ repertoires potentially associated with distinct nAbs were also characterized. Overall, our results demonstrate that rJS-ORF2-6-CON is a promising candidate for the development of a PRRS genetic engineered vaccine conferring cross protection. [ABSTRACT FROM AUTHOR]

To date, four species of porcine circoviruses (PCVs), including PCV1‐4, have been reported to exist in the clinical cases. Fast and effective differential detection is critical to monitor the infection and co‐infection status of PCVs for adopting reliable control strategies. However, currently available methods cannot simultaneously differentiate the four species of PCV strains. In this study, a quadruplex real‐time PCR assay based on TaqMan probes was developed for differential detection of PCV1‐4. The new quadruplex real‐time PCR assay exhibited satisfied specificity, sensitivity, repeatability and reproducibility. In addition, the new assay was applied to the detection of 120 clinical samples collected from 2016 to 2020 in Jiangsu province of China and compared with previously reported PCV1‐4 singleplex conventional PCR assays. Based on the clinical performance, the results from the quadruplex real‐time PCR and conventional PCR assays showed 100% agreement. A total of 47 samples were detected as PCV positive by the quadruplex real‐time PCR assay, including 1, 2, 1 samples were co‐infected with PCV1 and PCV4, PCV2 and PCV3, PCV2 and PCV4, respectively. Full‐length ORF2 sequencing and phylogenetic analysis supported the real‐time PCR results that 5, 34, 8 and 4 of the 51 PCV sequences were PCV1, PCV2, PCV3 and PCV4, respectively. This study provides a promising alternative tool for rapid differential detection of PCVs and confirms the coexistence of all species of PCV1‐4 strains in Jiangsu province in recent years. [ABSTRACT FROM AUTHOR]

Porcine epidemic diarrhea virus (PEDV) frequently causes diarrhea outbreaks. However, whether newly discovered enteric viruses such as porcine kobuvirus (PKV) and porcine astroviruses (PAstVs) are also correlated with diarrhea is still unclear. Diarrhea outbreaks were reported in a PEDV-vaccinated pig farm in Xinjiang Uygur Autonomous Region of China from 2019 to 2020. PEDV was a common pathogen detected in fecal samples by routine RT-PCR assays. The PEDV positive fecal sample was used for pathogenic analysis due to the failure isolation of PEDV. The challenged neonatal piglets appeared watery diarrhea within one day post infection (dpi) and all died within 6 dpi. Histopathological and immunohistochemical examinations supported that PEDV is a major pathogen causing intestinal lesions. To further explore enteric viruses associated with neonatal piglet diarrhea, metagenomics sequencing was performed for the diarrheic piglets. Remarkably, PKV was the most abundant virus (58.33%) followed by PEDV (34.45%) and PAstVs (7.22%), which were also confirmed by real-time RT-PCR assays. Significant in vivo replications of PEDV and PKV could only be observed in challenged piglets whilst PAstVs maintained similar virus loads in both challenged and mock infected piglets. Overall, this study provides first pathogenic and metagenomic evidence that significant proliferations of PEDV and PKV are closely associated with severe diarrhea in neonatal piglets, while PAstVs likely play limited roles in neonatal piglet diarrhea. • Pathogenic analysis suggested that PEDV is likely associated with 2019–2020 Xinjiang diarrhea outbreaks. • Metagenomics sequencing identified PEDV, PKV and PAstVs from severe diarrheic piglets. • Significant in vivo replications of PEDV and PKV were only detected in diarrheic neonatal piglets. • PAstVs maintained similar virus loads in both challenged and mock infected piglets during the animal study. • PEDV and PKV are closely associated with diarrheic diseases while PAstVs may play a limited role in neonatal piglet diarrhea. [ABSTRACT FROM AUTHOR]

Key message: Carbon (C) concentrations inCunninghamia lanceolata(Lamb.) Hook plantations differed significantly among tissue types and were greater for aboveground than belowground tissues. Plantation C stock increased with a developmental stage from young to mature to overmature, but at all stages, the majority occurred as soil organic carbon (SOC) and was more influenced by belowground fine roots than by aboveground litterfall. Context: Failing to account for tissue-specific variation in the C concentration can result in inaccurate forest C stock estimates. Aims: We aimed to quantify the relative magnitudes of C stock for Chinese fir plantations at different developmental stages. Specifically, we focused on assessing tissue-specific C concentrations and C dynamics return of above- and belowground litterfall. Methods: Carbon traits (C concentration, C flux, C stock, and distribution at tree and ecosystem scales) were quantified in a chronosequence of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) monoculture plantation stands at young (10), mature (22), and overmature (34 years old) developmental stages. Results: Carbon concentrations differed significantly among tissue types, with mean values of 48.5 ± 0.1% and 42.5 ± 0.2% for above- and belowground biomass, respectively. The aboveground tissue C concentration, tree- and plantation-scale C stock, and SOC stock depended on developmental stage. Carbon return in litterfall, tree C stock, and SOC increased from the young to the overmature stage. SOC stock accounted for the majority of plantation C stock at all developmental stages (78.3, 59.6, and 55.7% in the young, mature, and overmature stages, respectively) and was more highly influenced by belowground fine roots than aboveground litterfall. Carbon stocks in Chinese fir plantations were 86, 129, and 153 t ha−2 at the young, mature, and overmature stages. Conclusion: Prolonging Chinese fir rotation increases C sequestration potential and should be the focus of forest management strategies. The tissue-specific C concentrations provide detailed information for more accurate biomass C stock estimates for Chinese fir plantations and other subtropical coniferous forests. They indicate that current guidelines result in an overestimation of belowground biomass C stocks. Using the standard 0.47 biomass to C conversion factor, the belowground C stock would have been overestimated by 7.6–13.0% for the Chinese fir developmental stages investigated, while tree C stock would be underestimated by 0.08–3.24%. Therefore, developing species- and tissue-specific conversion factors are required for supporting C plantation and forest C accounting strategies. [ABSTRACT FROM AUTHOR]

Porcine reproductive and respiratory syndrome virus 1 (PRRSV-1) has been prevalent in more than 20 provinces of China. However, no PRRSV-1-specific vaccine is commercially available in China. To evaluate the feasibility of using a low virulent PRRSV-1 isolate against potential outbreaks caused by virulent Chinese PRRSV-1 isolates, here we evaluated the efficacy of a low virulent PRRSV-1 HLJB1 strain isolated in 2014 as live vaccine against a virulent PRRSV-1 SD1291 strain isolated in 2022. Genome-based phylogenetic analysis showed that both HLJB1 and SD1291 were grouped within BJEU06–1-like isolates. However, they shared only 85.27% genomic similarity. Piglet inoculation and challenge study showed that HLJB1 inoculation could reduce viremia but did not significantly alleviate clinical signs and tissue lesions. Virus neutralization test indicated that HLJB1 inoculation could induce homologous neutralizing antibodies (NAbs) but no heterologous NAbs at 42 dpi. In addition, flow cytometric analyses showed that no memory T follicular helper (Tfh) cells against SD1291 and SD1291-specific IFN-γ secreting cells were induced by HLJB1 pre-inoculation. These results supported that HLJB1 inoculation only provides partial cross-protection against SD1291 infection even though they are clustered within the same PRRSV-1 subgroup, which is closely related to the failure in conferring cross-protective adaptive immune responses. • HLJB1 and SD1291 are both BJEU06-1-like PRRSV-1 isolates. • HLJB1 inoculation only confers partial cross-protection against SD1291 challenge. • HLJB1 inoculation cannot induce memory Tfh cells against SD1291 infection. • HLJB1 inoculation may induce homologous NAbs but no heterologous NAbs. • HLJB1 inoculation cannot generate SD1291-specific IFN-γ secreting cells. [ABSTRACT FROM AUTHOR]

Abstract: Rosa chinensis ‘Pallida’ (Rosa L.) is one of the most important ancient rose cultivars originating from China. It contributed the ‘tea scent’ trait to modern roses. However, little information is available on the gene regulatory networks involved in scent biosynthesis and metabolism in Rosa. In this study, the transcriptome of R. chinensis ‘Pallida’ petals at different developmental stages, from flower buds to senescent flowers, was investigated using Illumina sequencing technology. De novo assembly generated 89,614 clusters with an average length of 428bp. Based on sequence similarity search with known proteins, 62.9% of total clusters were annotated. Out of these annotated transcripts, 25,705 and 37,159 sequences were assigned to gene ontology and clusters of orthologous groups, respectively. The dataset provides information on transcripts putatively associated with known scent metabolic pathways. Digital gene expression (DGE) was obtained using RNA samples from flower bud, open flower and senescent flower stages. Comparative DGE and quantitative real time PCR permitted the identification of five transcripts encoding proteins putatively associated with scent biosynthesis in roses. The study provides a foundation for scent-related gene discovery in roses. [Copyright &y& Elsevier]

Porcine parvovirus genotype 1 (PPV1) causes reproductive disorder in swine and is prevalent in China. Recently, six new genotypes of PPVs (PPV2 through PPV7) have also been detected in Chinese swine herds. However, the coinfection status of all these seven genotypes of PPVs (PPV1-7) in China was not clarified yet. In this study, we developed a panel of PPV1-7 PCR assays with satisfied specificity, sensitivity and reproducibility and then applied to the detection of PPV1-7 in 435 clinical samples collected from eight provinces of China in 2016-2020. A total of 55.40% samples (241 out of 435) were PPV positive, while PPV2 and PPV3 (both 22.53%) belonging to the genus of Tetraparvovirus were the most prevalent genotypes. Noticeably, PPV1-7 strains were more prevalent in nursery and finishing pigs than in suckling pigs. In addition, coinfection could be detected in all eight provinces and 27.36% (119/435) samples were coinfected with two to five genotypes of PPVs. Meanwhile, the coinfection of PPVs with PCV2 was 22.30% (97/435). Twenty complete genomes of representative PPV1-7 were determined, and phylogenetic analysis confirmed the genotyping results by sequence comparisons and PCR assays. Remarkably, the PPV7 HBTZ20180519-152 strain from domestic pig was recombined from parental JX15-like and JX38-like isolates from wild boars. Selective pressure analysis based on VP2 sequences of PPV1-7 showed that they were predominantly under negative selection, while few positive selection sites could be detected in VP2 of PPV7. Overall, this systematic investigation unveils high prevalence and coinfection of PPV1-7 in China from 2016 to 2020. IMPORTANCE Porcine parvoviruses (PPVs) are prevalent in China associating with reproductive failure in swine. The coinfection of seven genotypes of PPVs (PPV1-7) might have synergistic effects on PPV1 associated SMEDI syndrome. However, the coinfection status of PPV1-7 in China is not clear yet. This study showed that PPV1-7 strains are highly prevalent (55.40%) in China and mainly in nursery and finishing pigs in recent years. In addition, the coinfections of different genotypes of PPVs (27.36%) and PPVs with PCV2 (22.30%) are common. Geographic analysis indicated that different genotypes of PPVs are widely cocirculating in China. Intriguingly, a PPV7 strain from the domestic pig was detected as a recombinant from two wild boar isolates. Selective pressure analyses showed that PPV1-7 are mainly under purifying selection. Our findings provide the first systematic investigation on the prevalence, coinfection, and evolution of PPV1 through PPV7 in Chinese swineherds from 2016 to 2020.

Canopy litter is an important component of coarse woody debris (CWD), which affects nutrient and carbon cycling in forest ecosystems. For marcescent plant species (characterized by dead branches and leaves remaining in the canopy for several years before abscission), nutrient resorption from senescing leaves is an important nutrient conservation strategy. However, investigating the ecological function of canopy litter is challenging due to its limited accessibility and also the heterogeneous canopy microclimate in terms of light transmission, temperature and moisture. We studied the spatiotemporal distribution of canopy litter mass and seasonal dynamics of leaf nutrients and nutrient resorption during senescence in the canopy along a chronosequence of Chinese fir [Cunninghamia lanceolata (Lamb.) Hook] plantations in southeast China. The dry mass weight of dead branches and dead leaves in the canopy significantly increased with stand stage (14.6, 14.2, and 17.4 t ha -1 for young, middle-aged, and mature stands respectively), accounting for high proportions of total aboveground litter of 85.7%, 79.1% and 80.0%, respectively, along with annual litterfall production (2.44, 3.75, and 4.34 t ha -1 , respectively). The canopy height distribution of dead branches and leaves also increased with stand age, ranging from 0 to 4 m in young stands, 3-8 m in middle-aged stands, to 4-10 m in mature stands. The seasonal pattern of canopy litter mass was the inverse of litterfall production: canopy litter mass peaked, while litterfall production was lowest in winter. Mean N, P, K, and Mg nutrient resorption efficiencies across stands at each stage were 53.8-58.9%, 64.0-68.9%, 85.0-90.2%, and 46.5-56.6%, respectively, while Ca was not retranslocated from senescing leaves. In summary, Chinese fir plantations retain large amounts of dead branches and leaves in the canopy from which at least ~50% of the nutrients N, P, K and Mg are recycled, representing an important nutrient conservation strategy that has evolved to adapt to nutrient-limited habitats. Canopy litter therefore plays an important role in these forest plantation ecosystems and should be protected instead of being removed from the canopy to the forest floor., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Modified live vaccines (MLVs) have been utilized to combat porcine reproductive and respiratory syndrome (PRRS), which raises a serious concern about the MLV-derived PRRS virus (PRRSV) isolates. During the routine investigation of PRRSV in China, four lung samples collected from unvaccinated diseased pigs from 2016 to 2020 were detected as PRRSV positive. The PRRSVs shared high ORF5 identities to CH-1R, JXA1-R, TJM-F92 and RespPRRS MLV vaccines, respectively. The viruses were isolated in Marc-145 cells and denominated as SD1612-1, JS1703-21, JSTZ1907-714 and JSYC20-05-1. Genome comparison confirmed that these isolates share the highest genomic homologies to CH-1R (97.96%), JXA1-R (99.64%), TJM-F92 (99.00%) and RespPRRS MLV (99.57%) than any other known isolates. Genome-based phylogenetic analysis showed that SD1612-1 and CH-1R, JS1703-21 and JXA1-R, JSTZ1907-714 and TJM-F92, JSYC20-05-1 and RespPRRS MLV were grouped in the same branches. In addition, amino acids unique to corresponding vaccine attenuations were also identified in our isolates. Noticeably, amino-acids potentially associated with the virulence revision from MLV strains to parental virulent viruses were also identified in the MLV-derived isolates. Our results confirm that the four types of MLV-derived isolates are circulating and evolving in Chinese swine herds for years, which highlights the necessity for the fair use of PRRS MLVs., (Copyright © 2020. Published by Elsevier Ltd.)

Background: The HD-Zip transcription factors are unique to plants and play an essential role in plant growth, development and stress responses. The HD-Zip transcription factor family consists of a highly conserved homeodomain (HD) and a leucine zipper domain (LZ) domain. Although the HD-Zip gene family has been extensively studied in many plant species, a systematic study of the Eucalyptus HD-Zip family has not been reported until today. Here, we systematically identified 40 HD-Zip genes in Eucalyptus (Eucalyptus grandis). Besides, we comprehensively analyzed the HD-Zips of Eucalyptus by studying the homology, conserved protein regions, gene structure, 3D structure of the protein, location of the genes on the chromosomes and the expression level of the genes in different tissues., Results: The HD-Zip family in Eucalyptus has four subfamilies, which is consistent with other plants such as Arabidopsis and rice. Moreover, genes that are in the same group tend to have similar exon-intron structures, motifs, and protein structures. Under salt stress and temperature stress, the Eucalyptus HD-Zip transcription factors show a differential expression pattern., Conclusions: Our findings reveal the response of HD-Zip transcription factors under salt and temperature stresses, laying a foundation for future analysis of Eucalyptus HD-Zip transcription factors.

High genetic diversity and limited cross-protection are two major reasons for ineffective control of porcine reproductive and respiratory syndrome virus (PRRSV) infection. Therefore, it's important to dynamically monitor the prevalence of PRRSV for adopting appropriate control strategy. In this study, we analyzed PRRSV infection by detecting 712 clinical samples collected from 2016 to 2019 in China. Totally 100 samples were detected as PRRSV positive, including 2 and 98 samples were infected with PRRSV1 and PRRSV2, respectively. In addition, two out of the 98 PRRSV2 positive samples were co-infected with two distinct viruses. ORF5-based phylogenetic analysis showed that JXA1-like HP-PRRSV2 (lineage 8) and NADC30-like PRRSV2 (lineage 1) isolates are currently predominant, but QYYZ-like PRRSV2, CH-1a-like PRRSV2 and PRRSV1 isolates also co-exist in Chinese swine herds. In addition, two commercial MLV-derived viruses (TJM-F92-like and JXA1-R-like) were frequently detected. GP5 alignment also detected insertion and deletion in the extravirion domain. Our study presents the up-to-date PRRSV infection status and highlights the high genetic diversity of PRRSV currently circulating in China., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Porcine reproductive and respiratory syndrome virus (PRRSV) causes huge economic loss to the global swine industry. Even though several control strategies have been applied, PRRS is still not effectively controlled due to the continuous emergence of new variants and limited cross-protection by current vaccines. During the routine epidemiological investigation in 2017, two PRRSV variants were identified from a severe abortion farm and a clinically healthy farm, respectively. The viruses were isolated and denominated as XJ17-5 and JSTZ1712-12. Genomic sequencing indicated that their genomes are both 14,960 bp in length sharing 99.45% nucleotide identity. Sequence alignments identified a discontinuous 30-amino-acid deletion and a continuous 120-amino-acid deletion in nsp2 of both isolates. Genome-based phylogenetic analysis confirmed that XJ17-5 and JSTZ1712-12 belong to the HP-PRRSV subtype but form a new branch with other isolates containing the same 150-amino-acid deletion in nsp2 . Pathogenic analysis showed that XJ17-5 is highly virulent causing 60% mortality, while JSTZ1712-12 is avirulent for piglets. Furthermore, fragment comparisons identified 34-amino-acid differences between XJ17-5 and JSTZ1712-12 that might be associated with the distinct virulence. The identification of highly homologous HP-PRRSV variants with new genetic feature and distinct virulence contributes to further analyze the pathogenesis and evolution of PRRSV in the field.